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* [Bug tree-optimization/95408] New: Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand
@ 2020-05-29 9:40 gabravier at gmail dot com
2021-04-26 1:15 ` [Bug tree-optimization/95408] " pinskia at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: gabravier at gmail dot com @ 2020-05-29 9:40 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95408
Bug ID: 95408
Summary: Failure to optimize bitwise and with negated
conditional using the same operand to conditional with
decremented operand
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
bool f(int x)
{
return x & -((unsigned)x < some_constant);
}
This can be optimized to `return (unsigned)(x - 1) < (some_constant - 1);`.
This transformation is done by LLVM, but not by GCC.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/95408] Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand
2020-05-29 9:40 [Bug tree-optimization/95408] New: Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand gabravier at gmail dot com
@ 2021-04-26 1:15 ` pinskia at gcc dot gnu.org
2023-05-13 5:47 ` pinskia at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-04-26 1:15 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95408
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/95408] Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand
2020-05-29 9:40 [Bug tree-optimization/95408] New: Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand gabravier at gmail dot com
2021-04-26 1:15 ` [Bug tree-optimization/95408] " pinskia at gcc dot gnu.org
@ 2023-05-13 5:47 ` pinskia at gcc dot gnu.org
2023-08-23 2:36 ` pinskia at gcc dot gnu.org
2023-09-16 6:25 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-05-13 5:47 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95408
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Assignee|unassigned at gcc dot gnu.org |pinskia at gcc dot gnu.org
Last reconfirmed| |2023-05-13
Status|UNCONFIRMED |ASSIGNED
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
For unsigned x (to simplify things first).
In forwardprop4 we have
_1 = x_4(D) <= 121211;
_3 = _1 ? x_4(D) : 0;
_5 = _3 != 0;
This could be done as:
x_4(D) <= 121211 ? x_4(D) != 0 : 0
Which then would be:
(x_4(D) <= 121211 & x_4(D) != 0)
((x_4(D) - 1) <= 121210)
So I have a patch which does the second step into the 3rd expression (there is
another bug or 2 about it). the 3rd expression into the final is already done.
It is just the first that needs to happen to written up.
Something like this for the first step.
(for op (tcc_comparison)
/* (c ? a : CST0) op CST1 --> c ? (a op CST1) : (CST0 op CST1) */
(simplify
(op (cond:s @0 @1 CONSTANT_CLASS_P@2) CONSTANT_CLASS_P@3)
(cond! @0 (op @1 @3) (op @2 @4)))
So mine.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/95408] Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand
2020-05-29 9:40 [Bug tree-optimization/95408] New: Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand gabravier at gmail dot com
2021-04-26 1:15 ` [Bug tree-optimization/95408] " pinskia at gcc dot gnu.org
2023-05-13 5:47 ` pinskia at gcc dot gnu.org
@ 2023-08-23 2:36 ` pinskia at gcc dot gnu.org
2023-09-16 6:25 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-08-23 2:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95408
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
In forwprop1 we have:
_2 = x.0_1 <= 121210;
_3 = (int) _2;
_4 = _3 * x_5(D);
_6 = _4 != 0;
since _3 is zero_one_valued we could do instead:
```
(for cmp (ne eq )
bitop (bit_and bit_ior)
(simplify
(cmp (mult zero_one_valued_p@0 @1) integer_zerop@2)
(bitop! (convert @0) (ne @1 @2))))
```
And we should be able to get it earlier on.
Still mine and I will look into the above.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/95408] Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand
2020-05-29 9:40 [Bug tree-optimization/95408] New: Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand gabravier at gmail dot com
` (2 preceding siblings ...)
2023-08-23 2:36 ` pinskia at gcc dot gnu.org
@ 2023-09-16 6:25 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-09-16 6:25 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95408
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
URL| |https://gcc.gnu.org/piperma
| |il/gcc-patches/2023-Septemb
| |er/630651.html
Keywords| |patch
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I was looking for this one when I wrote
https://gcc.gnu.org/pipermail/gcc-patches/2023-September/630651.html .
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2023-09-16 6:25 UTC | newest]
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2020-05-29 9:40 [Bug tree-optimization/95408] New: Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand gabravier at gmail dot com
2021-04-26 1:15 ` [Bug tree-optimization/95408] " pinskia at gcc dot gnu.org
2023-05-13 5:47 ` pinskia at gcc dot gnu.org
2023-08-23 2:36 ` pinskia at gcc dot gnu.org
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